Quake Expert Says Yellowstone ‘Swarm’ Not A Signal of ‘Super Volcano’

In the last two weeks, there have been nearly 900 earthquakes recorded in Yellowstone National Park, including a 4.5 magnitude temblor on June 15.

Earthquake specialist Mike Stickney with the Montana Bureau of Mines and Geology at Montana Tech in Butte, said earthquake swarms are common in an area as seismically active as Yellowstone National Park.

"Swarms are frequently associated with volcanic regions, and Yellowstone is a large volcanic region," Stickney said. "People believe that the swarms are the result of geothermal fluids that are migrating upward to the crust finding their way into fractures and faults in the rick and temporarily lubricating patches on those faults and allowing them to slip as small earthquakes."

Stickney said the 4.5 quake was felt inside the park, but almost all the hundreds of others only registered on seismographic equipment.

Stickney said the quake swarm is not a precursor to what is popularly called a 'super eruption' of the giant caldera that fills a large area of the park.

"The current activity is centered 12 miles northwest of the edge of that caldera, so it's really outside of the area where partially molten rock may exist at depth," he said. "So, there's no obvious connection between any current volcanic process and these earthquakes."

Stickney said the earthquake swarms are simply another fascinating aspect of the country's first national park.

The attached image is a 24 hour record of ground motion recorded by the Maple Creek seismograph station, operated by the University of Utah Seismograph Stations, located about a mile from the earthquake swarm in northwestern Yellowstone National Park.